How to calculate photovoltaic savings

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Saving money with photovoltaic panels is certainly possible. Installing solar panels has many advantages, and one of the most important ones is how much money we can save, which is particularly relevant in these difficult times.

With a self-consumption installation that uses photovoltaic panels you can reduce your electricity bill by up to 50%. In addition, there are regional and local subsidies for solar panels that can help the system pay for itself much faster.

The question is: Is there any way of knowing the real savings when using photovoltaic energy? How can we calculate it?

Steps to calculate the savings due to photovoltaic energy

Before we start, we would like to remind you that solar energy is still a growing industry. So, before you decide to install solar panels in your home, you should choose an approved installer or installation company like MyGreenHouse. You can request information from them and they will assess the project and then, together, you can decide how best to finance your system.

After that, it’s possible to start calculating how much money you can save with solar panels.

Overall, going solar at home can save you thousands of euros – for a number of reasons.

The first is that you can benefit from many incentives and subsidies.

In addition, you should take into account the money that you’ve already saved, or that you won’t have to pay your electricity company for the next twenty years, which is the expected lifespan of this type of installation.

Likewise, regarding the current electricity prices, it is likely that, in the coming months, energy tariffs will increase. This will increase bills, meaning there will be even more savings with photovoltaic energy.

So, let’s have a closer look at how to calculate the likely savings:

Step 1: Consult your electricity bills

In order to find out the total savings you will make with photovoltaic energy, you’ll need to know your home’s electricity usage history. Nowadays, this is quite simple thanks to electricity meters, which record the energy consumption, hour by hour, during the 8760 hours of the year.

If you haven’t got this information to hand, you can request it directly from your electricity provider. The procedure is simple, and you will only be asked for information such as the name of the contract holder and contract reference, ID number, telephone number, contact details and the CUPS supply code.

Step 2: Calculate the energy generated by the photovoltaic system

The next step is to find out how much electricity your solar panel installation will produce. The easiest way is to calculate how much a standard 1kW installation will generate and then multiply the figure by your system’s kilowattage. For example, if your installation is 3.5 kW, you would simply multiply the output by 3.5.

The European Union has a tool to calculate your photovoltaic electricity generation. You will need to enter some data such as your house coordinates, the roof’s approximate angle of inclination, and the orientation or inclination of your solar panels.

Another way to find out the electricity your photovoltaic installation will generate is to ask your installation company directly.

Step 3: Calculate the self-consumption rate

If you know how much energy you consume and how much energy your PV panels produce, calculating your self-consumption rate is relatively straightforward.

However, there are a few things you should remember. The higher the potential of the photovoltaic installation, the lower the self-consumption rate. Likewise, the higher the household consumption, the higher the self-consumption rate.

On this basis, all you have to do is compare the expected consumption over the 8760 hours of the year with the expected electricity generation over the same period, taking into account the hour changes in March and October.

Having said this, the savings of a PV system will also depend on whether the system has batteries or not. If the system does not have batteries, our recommendation is to multiply the value by 0.8 or 0.9. In systems with batteries, the calculation is more complicated because it depends not only on the production/consumption ratio, but also on the hourly rates and the lifespan of the batteries.

If the system doesn’t have batteries, the typical percentage of self-consumption is around 55-65%, depending on consumption habits. On the other hand, when batteries are installed, this percentage increases to 70-85%, sometimes reaching as much as 92-97%.

Step 4: Calculate energy savings easily

By multiplying the total self-consumption energy by the price of self-consumption energy, you will get a first estimate of what the real savings will be with your PV installation.

As you will probably be on an hourly tariff, you can factor in the cheapest electricity price during peak hours and the standard kWh price for the rest.

You could also add the cheapest price for grid feed-in, but keep in mind that these are only subtracted from the energy bill, i.e. they can never be refunded.


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